The present invention relates to power switches, and more particularly to a power switch equipped with a position holding mechanism that comprises a spring and an extension rod.
The main usage of a power switch is to control the power to open and close a circuit. The power switch can be divided into different types according to structure, such as the common push switch and rocker switch.
Please refer to FIG. 1 for a cross-sectional view of a conventional rocker switch, which comprises a common contact point 70, a closed circuit contact point 71, a movable contact point 72 permanently coupled to the common contact point 70, a rocking button 73 for coupling the movable contact point 72 and selectively rocking the movable contact point 72 between a close circuit position and an open circuit position, and a position holding spring 75. Such a position holding spring 75 is a compressed spring with one end passing into the bottom 74 of the rocking button 73 and the other end pressing against the movable contact point 72. Regardless of the rocking button 73 position either set to the close circuit position (i.e. the position where the close circuit contact point is touching the movable contact point) or the open circuit position (i.e. the position where the open circuit contact point is not touching the contact point), the position holding spring 75 is compressed and accumulates with energy, and a deformation is produced by twisting the position holding spring 75 along the axial direction. In FIG. 1, the position holding spring 75 produces a reaction due to the compression, and produces a pushing force at the point P of the rocking button 73. Such pushing force pushes the rocking button 73 to rock about its pivotal axis, and the rocking button 73 is pushed by the position holding spring 75 to stop when one of its sides presses against the bottom base 76 of the rocker switch. Such relation will be changed alternatively under the operation of repeatedly switching the rocking button 73, and the movable contact point 72 will be pushed to the close circuit position (i.e. the position where the close circuit contact point is in touch with the movable contact point) or the open circuit position (i.e. the position where the open circuit contact point is in touch with the movable contact point) as the position holding spring 75 is twisted and deformed repeatedly.
However, the position holding spring 75 according to the aforementioned prior art has two main functions: one is to use a rebounding force produced by the permanent compression to push the rocking button 73 and select the close circuit position or open circuit position; and the other is to carry out the mission of flipping the movable contact point 72 when the position holding spring 75 is twisted to deform repeatedly. If such rocker switch is used in an environment of higher temperature, such as being installed in an oven, the repeated twisting and deformation will cause a permanent deformation to the compressed spring very easily. Therefore, the rocker switch cannot be kept in the close circuit position or an open circuit position. After a long-time use, the position holding spring 75 is loosened and the rocker switch no longer can keep a safe distance (such as 3 mm according to the European safety regulation) between the movable contact point and the close circuit contact point even the rocker switch is set to the close circuit position. Further, there are prior arts as disclosed in U.S. Pat. Nos. 4,431,880 and 5,950,812 teaching more complicated structures of the rocker switch.
The primary objective of the present invention is to provide a rocker switch with good heat-resistance. The rocker switch according to the present invention redesigns the position holding mechanism to improve the reliability of the movement and the heat-resistance of the rocker switch. For the position holding mechanism of the invention, an extension rod with one end passing into a rocking button and the other end connecting to a spring are used to change the position of the force acting between the spring and the rocking button and the force acting on the spring in order to improve the life of the spring and the heat resistance.
Another objective of the present invention is to provide a rocker switch with a high reliability. The position holding mechanism designed for the invention includes an extension rod with one end passing into the rocking button, and the other end of the extension rod and one end of the spring are extended into a movable contact point. Therefore, the extension rod will directly link the contact points to assure the reliability of movement when the rocking button is clicked.
To make it easier for our examiner to understand the objective of the invention, its structure, features, and performance, we use a preferred embodiment together with the attached drawings for the detailed description of the invention.